I don't, that would be a stupid thing to think. Anyone who's spent time running around in a Noddy suit with a respirator on knows that.Stress, energy and immunity.
All linked boyo.
What makes you think you can perform the same with a mask on than with it off?
But that's not CO2. Also your immune system is always impacted by physical activity. Too low damages it, too high damages it. That's pacing yourself, not CO2.
One of your many problems is that you assume too much.